1. Field of the Invention
The present invention relates to a sheet conveying unit configured to convey a sheet while correcting a skew thereof and an image forming apparatus including the same.
2. Description of the Related Art
Hitherto, an image forming apparatus forming an image on a sheet is provided with a sheet conveying unit configured to convey the sheet while correcting a skew of the sheet conveyed to an image forming portion in order to form the image on the sheet without inclination. For example, International Publication No. 2011/048668 discloses a sheet conveying unit including a shutter member biased in a direction opposite to a sheet conveying direction and correcting a skew by abutting a front end of a sheet against an abutting surface of the shutter member.
The sheet conveying unit described in International Publication No. 2011/048668 includes the shutter member turning in one direction. The shutter member is biased by a bias portion such that the abutting surface is positioned at a standby position after turning by being pushed by the sheet. The bias portion includes a bias spring, generates a reaction force against the sheet in the shutter member when the front end of the sheet abuts against the abutting surface, and generates a force for positioning a next abutting surface at the standby position after when a rear end of the sheet passes through.
However, because the sheet conveying unit described above generates the reaction force when the front end of the sheet abuts against the abutting surface by the bias force of the bias spring, there is a possibility that the front end of the sheet is flawed by dents or the like when the front end of the sheet abuts against the abutting surface if the bias force is large. There is also another possibility that the conveyance of the sheet is delayed when the sheet pushes and turns the shutter member if the bias force is large. Meanwhile, it is preferable to increase the bias force of the bias portion to position the shutter member reliably at the standby position after when the rear end of the sheet passes through. Thus, it is hard to achieve both the prevention of the dent and delay of the sheet and the reliable return of the shutter member to the standby position by the configuration in which the shutter member is biased by the bias portion.